Solid phase micro-extraction (SPME) is a common sampling technique which uses a syringe-like sample collection device to perform analyte collection, concentration, and separation without the use of solvents or the need for exhaustive extractions. Such SPME collection devices have an active portion usually consisting of a fused silica fiber coated with an active absorbent or media. The coated SPME fiber is typically housed in the needle (used for piercing a septum) of the syringe-like SPME device, and can be mechanically extended/retracted. In the SPME sampling process, a SPME fiber is introduced into a fluid carrier/sampling environment in the field (e.g. sampling atmosphere, volume, or space, such as a headspace) so that the SPME fiber is exposed to trace analytes (e.g. volatile organics) in the sampling environment and adsorbs and concentrates the analytes on the polymer coating. Exposed fiber is then inserted into a gas chromatagraph (GC) where the collected analytes are desorbed and separated, and a mass spectrometer provides spectral information of the analytes detailing their chemical composition.
However, traditional SPME sampling is limited by the fact that it is traditionally a “one shot” technique, where a sample extracted from a sampling environment using a SPME fiber/device is used up in the desorbtion/analysis step such that additional analysis cannot be performed with the same SPME fiber/device without re-sampling the sampling environment in the field. By the time another SPME extraction can be done, however, the sampling environment can be changed or altered or may be totally unavailable or dissipated. As such, quantitation of the sample environment may be limited. Moreover, the reliance on a single exposed SPME fiber as the representative measure of a sampling atmosphere may be unduly risking because of the fragile nature of SPME fiber and the potential loss of data results due to fiber damage or contamination. And furthermore, a single fiber type may not collect all analytes of interest. Thus, it can be seen that “one shot” sampling results are subject to many factors that may limit or completely eliminate useable data.
What is needed therefore is a SPME sampling apparatus and procedure that will eliminate the “one shot” problems associated with traditional SPME sampling and analysis by enabling fluid samples (e.g. sample atmospheres from a headspace) to be sub sampled and held stable for weeks at a time, during which time organic constituents are kept stable from breakdown. Furthermore, such a SPME sampling apparatus and procedure would enable multiple samplings of the sample atmosphere without a loss of the original sample atmosphere composition.